Emergency warning light switching system

ABSTRACT

An emergency warning light switching system for motor vehicles employs a solid state oscillator circuit which controls the alternate energization of vehicle lamps, such as, the vehicle headlamps. A unijunction transistor oscillator-bistable multivibrator arrangement supplies alternate pulses to a gate network. The pulses are amplified and alternately supplied to the vehicle lamps. An oscillator over-ride arrangement is provided, whereby the vehicle lamps may be energized simultaneously.

22 Filed:

United States Patent 1 Platte 1 1 May 8,1973

I54] EMERGENCY WARNING LIGHT SWITCHING SYSTEM [76] Inventor: Robert F.Platte, 810 Kay'Coun, Laurel, Md. 20810 Nov. 16, 1970 [21] Appl. N0.:89,562

52 U.S.Cl. ..340/76,3l5/82,340/83 51 1111.0. ..B60ql/46 [58]FieldofSearch ..340/76,83,33l;

[56] References Cited UNITED STATES PATENTS De Bolt et al ..307/4l X 3,113,241

Yonushka 3,376,472 4/1968 Taylor et a1. ..340/83 X 3,391,304 7/1968Fabry 340/83 X 3,488,558 1/1970 Grafton 340/83 X 2,932,814 4/1960Wilfert ..340/76 \IERGENCY LIGHTS VM nun Ill; 1

nun

2,578,284 12/1951 Bowman ..340/55 X 2,655,642 10/1953 Ayres et al.

3,113,293 12/1963 Breese et al. "340/83 X 3,500,315 3/1970 Shimada..340/82 Primary Examiner.l0hn W. Caldwell Assistant Examiner-Kenneth N.Leimer AttorneyCraig, Antonelli & Hill [57] ABSTRACT An emergencywarning light switching system for motor vehicles employs a solid stateoscillator circuit which controls the alternate energization of vehiclelamps, such as, the vehicle headlamps. A unijunction transistoroscillator-bistable multivibrator arrangement supplies alternate pulsesto a gate network. The pulses are amplified and alternately supplied tothe vehicle lamps. An oscillator over-ride arrangement is provided,whereby the vehicle lamps may be energized simultaneously.

10 Claims, 1 Drawing Figure nun EMERGENCY WARNING LIGHT SWITCHING SYSTEMThis invention relates to emergency warning light systems for motorvehicles and, more particularly, to the alternate flashing of vehiclelamps, such as the vehicle headlamps, through the use of solid stateelectronic circuitry.

Various types of warning light systems have been employed in emergencyvehicles and have generally included roof-mounted flashing lights. Inorder to distinguish certain vehicles such as police vehicles from othertypes of emergency vehicles, jurisdictions have adopted the use ofroof-mounted, particularly dometype, blue flashing lights in place ofthe common amber or red lights. However, it is difficult for the humaneye to distinguish the color blue at a distance; also, human side visionis generally poor in distinguishing between colors.

To overcome the limitations of using the color blue in roof-mountedflashing light arrangements, while still distinguishing betweenemergency vehicles, it has been proposed to use vehicle lamps such asthe headlamps, as the warning light system in place of or in addition tothe roof-mounted lights. It has also been found that where the vehiclelamps, such as the headlamps, are of the type which emit a bright bluecolor, reflection of the bright blue light from metallic or mirroredsurfaces of other vehicles provide other drivers with a verysatisfactory warning of the approach of an emergency vehicle. This isparticularly advantageous where the emergency vehicle is approachingfrom the rear, as the light reflecting from surfaces such as the rearview mirror, metallic interior surfaces, etc. warns the driver of theapproach of the emergency vehicle. A roofmounted dome-type light, on theother hand, is not readily detected by the driver.

BRIEF SUMMARY OF THE INVENTION Briefly, the present invention isdirected to a warning light system which employs solid state circuitryto control the alternate flashing of vehicle mounted lamps. Aunijunction transistor oscillator delivers a series of pulses to asequential logic circuit, such as a bistable flipflop which has its setand reset outputs gated and amplified to the respective vehicle lamps.An over-ride is also provided to activate both lamps simultaneously,irrespective to the generation of flashing pulses by the oscillator.

It is, therefore, a primary object of the present invention to provide anew and improved emergency vehicle warning light system.

It is a further object of the present invention to provide a vehiclelamp switching system whereby vehiclemounted lamps may be alternatelyflashed during an emergency and may also be connected for normalsimultaneous use. i

It is another object of the present invention to provide a vehicleemergency warning light switching system which employs solid statecircuitry, to thereby avoid problems such as the sticking, wearing andbounce of movable contacts.

It is an additional object of the present invention to provide anemergency warning light system employing vehicle headlamps, having ahigh beam over-ride, thus making the system applicable to a two or fourlamp system.

Other objects, features and many of the attendent advantages of thisinvention will be appreciated more readily as the same becomesunderstood by reference to the following detailed description, whenconsidered in connection with the accompanying drawing, wherein:

The FIGURE is a schematic diagram of the emergency warning lightswitching system of the present invention.

In the FIGURE, a first terminal A, to which a voltage is supplied foractuating vehicle lamps, in an emergency flashing condition, isconnected to resistors R, R and R Resistors R, and R, are connected tothe emitter and base 1, respectively, of unijunction transistor 0,.Connected between ground and the emitter and the other base 2 oftransistor Q, are a capacitor C, and a resistor R respectively.Together, transistor Q, and elements R,, R, and R and C, form arelaxation oscillator which produces pulses at a preferred rate ofapproximately two per second.

The output of transistor Q, is coupled across resistor R,, and issupplied via capacitor C to the toggle input of flip-flop U,. A resistorR is connected between ground and capacitor C, to discharge the latter.Flip-flop U, is preferably an integrated circuit bi-stable, toggleflipflop producing symmetrical square wave outputs at its Set and Resetoutputs, with half periods equal to the period between pulses fed to thetoggle input of flip-flop U,.

Also connected to flip-flop U, are resistor R capacitor C and diode D,which forms a by-pass bias center for the flip-flop U,.

Connected to the respective Set" and Reset outputs of flip-flop U, arediodes D and D These diodes, together with diodes D and D andtransistors Q and 0,, respectively, form two-two input positive NOR"gates. Capacitor C which has one side thereof grounded, and resistor R,are connected to the common junction of diode D and D Via resistor R, apositive voltage is supplied from terminal B.

The emitters of the symmetrically connected transistors Q and Q, aregrounded while their respective collectors are connected throughresistors R and R, to the bases of transistors Q and Q Transistors Q andQ5, together with associated transistors Q and 0,, form Darlingtoncoupled amplifiers. Resistors R, and R,, are connected to resistors Rand R and to the emitters of transistors Q and Q respectively. Thecommon connection of resistors R,,,, R,, and the emitters of transistorsQ and Q, is connected to a terminal C to which a positive voltage isapplied. Resistor pairs R, R and R R,, function as collector loads fortransistors Q, and Q, and bias resistors for the Darlington amplifiers 0-0,, and Q,,-Q,. The outputs of the Darlington amplifiers are connectedto load terminals T, and T, which, in turn, may be connected to thevehicle lamps L, and L respectively.

The operation of the circuit of the present invention has three separatemodes, each of which will be described below.

' Mode l Emergency Lights Only With terminal B open, a voltage of 10 to15 volts is applied to terminals A and C. Capacitor C, charges throughresistor R, until the voltage across capacitor C, exceeds the firingthreshold voltage of transistor Q, at

which time transistor Q fires, discharging capacitor C through theemitter-base 2 junction of transistor Q, and through resistor R Thedischarge current produces, across resistor R a positive voltage pulsewhich is capacitively coupled to the clock or toggle input of flipflop UBetween pulses, resistor R discharges capacitor C As transistor Qproduces a chain of positive pulses, which are coupled to flip-flop Uflip-flop U generates square waves at half the clock frequency providedby transistor 0,.

Diodes D and D couple alternative positive signals to transistors Q andQ Since terminal B is open, no positive bias is simultaneously appliedto the bases of transistors Q and through diodes D and D so thattransistors Q and Q are driven alternately into saturation for an equalduration according to the frequency of the output of transistor 0,. Theoutputs of transistors Q and 0:, are amplified by the subsequentDarlington amplifier stages, while operating in the saturation stateonce triggered on. When either transistor 0,, or Q, saturates,energizing current is delivered to one of the lamps L and L throughterminals T and T respectively. In this manner, each of the lamps isalternately energized at a frequency determined by the unijunctiontransistor oscillator and flip-flop U Mode 2 Over-ride delivered tolamps L and L simultaneously. Thus, the

flashing of the lamps is over-riden by the application of a voltage toterminal B.

Mode 3 Independent Operation With voltage applied to terminals B and Conly, the lamps operate in a standard simultaneous mode. Thus, the lampscan be energized independently of the generation of pulses by theoscillator circuit. This is particularly desirable where the vehicleheadlamps are used. The circuit operates substantially in the samemanner as in Mode 2, except that no pulses are delivered to diodes D andD.,.

In Modes 2 and 3, the use of the logic gate arrangement permitsover-ride thus making the circuit of the present invention applicable totwo or four lamp systems. I

From the foregoing description, it can be appreciated that the inventionprovides a new and improved energizing light switching system. Becausethe circuit is all solid state, the inherent defects of moving contacts,including wear and noise are eliminated. Furthermore, the term vehicleas used herein is not restricted to automobiles but may refer to othertypes of vehicles such as aircraft, boats, etc., as the warning systemof the present invention is readily usable therein.

Having thus described the emergency light switching system of thepresent invention, it is believed obvious that other modifications andvariations of the invention are possible in the light of the aboveteachings. It is, therefore, to be understood that changes may be madein a particular circuit of the invention described which are in the fullintended scope of the invention as defined by the appended claims.

I claim:

' 1. ln an emergency warning light switching system for motor vehicles,employing the vehicle head lamps for the warning lights, the improvementcomprising:

first means for generating a series of energizing pulses;

second means, responsive to the pulses generated by said first means,for delivering said energizing pulses alternately to said vehicleheadlamps, said second means including a first logic gate circuit and apair of amplifiers coupled in series with said logic gate circuit fordelivering alternate amplified pulses to said headlamps; and

third means connected to said first logic gate circuit,

for simultaneously energizing said headlamps irrespective of theapplication of said energizing pulses to said headlamps, so as toprovide an emergency light over-ride to said lamps, wherein saidsimultaneous energizing third means comprises a second logic gatecircuit connected to said first logic gate circuit, and means fordelivering a supply voltage to said second logic circuit, whereby theapplication of an energizing signal to one of said first and secondlogic circuits will energize said headlamps.

2. An emergency warning light switching system according to claim 1,wherein said pulse generating means comprises a unijunction transistoroscillator and said second means further includes a bistable flip-flopconnected in series with said unijunction transistor oscillator, andfurther including means for delivering an energizing voltage to saidoscillator and to said flipflop, the output of said flip-flop beingcoupled to said pulse delivering amplifiers.

3. An emergency warning light system according to claim 2, wherein saidfirst logic gate circuit includes first and second diodes connected tothe respective outputs of said flip-flop and further including first andsecond symmetrically arranged transistors connected between said diodesand said amplifiers, for amplifying the output of said diodes.

4. An emergency warning light system according to claim 3, wherein saidsecond logic gate circuit includes third and fourth diodes connected tosaid first and second transistors for delivering an over-ride signal tosaid transistors irrespective of the application of alternate pulsesthereto from said first and second diodes.

5. An emergency warning light system according to claim 4, wherein eachamplifier in said pair of amplifiers comprises a Darlington connectedamplifier.

6. An emergency warning light system according to claim 5, furtherincluding a differentiator network connected between the output of saidunijunction transistor oscillator and the input of said flip-flop.

7. An emergency warning light system according to claim 6, furtherincluding a by-pass bias network connected between said energizingvoltage delivering means and said flip-flop.

8. An emergency warning light switching system for a motor vehicle,particularly one employing the vehicle headlamps for the warning lights,comprising:

first means for generating a series of pulses;

second means, having a pair of outputs and having an input connected toreceive said pulses generated by said first means, for providing aseries of alternate energizing pulses at said pair of outputs inresponse to the pulses generated by said first means;

third means, having a pair of inputs, which are separately connected tothe outputs of said second means, for delivering alternate ones of saidenergizing pulses to a pair of lamp terminals for alternately energizinglamps connected thereto; and

fourth means, connected to both inputs of said third means, forsupplying an over-ride input signal to each input of said third means,to provide an energizing signal to both lamp terminals, irrespective ofthe generation of pulses by said first means, wherein said first meanscomprises a transistor oscillator circuit, said second means comprises abistable element, connected to said transistor oscillator, for providingsaid series of alternate energizing pulses at the pair of outputsthereof, said third means comprises a first logic circuit and a pair ofamplifier circuits coupled in series with cording to claim 8, whereinsaid first logic circuit includes first and second diodes connected tothe respective outputs of said bistable element and further includesfirst and second symmetrically arranged transistors connected betweensaid diodes and said amplifiers for amplifying the output of saiddiodes.

10. An emergency warning light switching system according to claim 9,wherein said second logic circuit includes third and fourth diodesconnected to said first and second transistors for delivering anover-ride signal to said transistors irrespective of the application ofalternate pulses thereto from said first and second diodes,

1. In an emergency warning light switching system for motor vehicles,employing the vehicle head lamps for the warning lights, the improvementcomprising: first means for generating a series of energizing pulses;second means, responsive to the pulses generated by said first means,for delivering said energizing pulses alternately to said vehicleheadlamps, said second means including a first logic gate circuit and apair of amplifiers coupled in series with said logic gate circuit fordelivering alternate amplified pulses to said headlamps; and third meansconnected to said first logic gate circuit, for simultaneouslyenergizing said headlamps irrespective of the application of saidenergizing pulses to said headlamps, so as to provide an emergency lightover-ride to said lamps, wherein said simultaneous energizing thirdmeans comprises a second logic gate circuit connected to said firstlogic gate circuit, and means for delivering a supply voltage to saidsecond logic circuit, whereby the application of an energizing signal toone of said first and second logic circuits will energize saidheadlamps.
 2. An emergency warning light switching system according toclaim 1, wherein said pulse generating means comprises a unijunctiontransistor oscillator and said second means further includes a bistableflip-flop connected in series with said unijunction transistoroscillator, and further including means for delivering an energizingvoltage to said oscillator and to said flip-flop, the output of saidflip-flop being coupled to said pulse delivering amplifiers.
 3. Anemergency warning light system according to claim 2, wherein said firstlogic gate circuit includes first and second diodes connected to therespective outputs of said flip-flop and further including first andsecond symmetrically arranged transistors connected between said diodesand said amplifiers, for amplifying the output of said diodes.
 4. Anemergency warning light system according to claim 3, wherein said secondlogic gate circuit includes third and fourth diodes connected to saidfirst and second transistors for delivering an over-ride signal to saidtransistors irrespective of the application of alternate pulses theretofrom said first and second diodes.
 5. An emergency warning light systemaccording to claim 4, wherein each amplifier in said pair of amplifierscomprises a Darlington connected amplifier.
 6. An emergency warninglight system according to claim 5, further including a differentiatornetwork connected between the output of said unijunction transistoroscillator and the input of said flip-flop.
 7. An emergency warninglight system according to claim 6, further including a by-pass biasnetwork connected between said energizing voltage delivering means andsaid flip-flop.
 8. An emergency warning light switching system for amotor vehicle, particularly one employing the vehicle headlamps for thewarning lights, comprising: first means for generating a series ofpulses; second means, having a pair of outputs and having an inputconnected to receive said pulses generated by said first means, forproviding a series of alternate energizing pulses at said pair ofoutputs in response to the pulses generated by said first means; thirdmeans, having a pair of inputs, which are separately connected to theoutputs of said second means, for delivering alternate ones of saidenergizing pulses to a pair of lamp terminals for alternately energizinglamps connected thereto; and fourth means, connected to both inputs ofsaid third means, for supplying an over-ride input signal to each inputof said third means, to provide an energizing signal to both lampterminals, irrespective of the generation of pulses by said first means,wherein said first means comprises a transistor oscillator cIrcuit, saidsecond means comprises a bistable element, connected to said transistoroscillator, for providing said series of alternate energizing pulses atthe pair of outputs thereof, said third means comprises a first logiccircuit and a pair of amplifier circuits coupled in series with saidfirst logic circuit, and wherein said fourth means comprises a secondlogic circuit connected to said first logic circuit, and means fordelivering a supply voltage to said second logic circuit, whereby theapplication of an energizing signal to one of said first and secondlogic circuits will energize said headlamps.
 9. An emergency warninglight switching system according to claim 8, wherein said first logiccircuit includes first and second diodes connected to the respectiveoutputs of said bistable element and further includes first and secondsymmetrically arranged transistors connected between said diodes andsaid amplifiers for amplifying the output of said diodes.
 10. Anemergency warning light switching system according to claim 9, whereinsaid second logic circuit includes third and fourth diodes connected tosaid first and second transistors for delivering an over-ride signal tosaid transistors irrespective of the application of alternate pulsesthereto from said first and second diodes.